A typical computer system includes at least a microprocessor and some form of memory. The microprocessor has, among other components, arithmetic, logic, and control circuitry that interpret and execute instructions necessary for the operation and use of the computer system. FIG. 1 shows a typical computer system (10) having a microprocessor (12), memory (14), integrated circuits (ICs) (16) that have various functionalities, and communication paths (18), i.e., buses and wires, that are necessary for the transfer of data among the aforementioned components of the computer system (10).
As circuit elements continue to get smaller and as more and more circuit elements are packed onto an IC, ICs (16) dissipate increased amounts of power, effectively causing ICs (16) to run hotter. Consequently, increased operating temperatures create a propensity for performance reliability degradation. Thus, it is becoming increasingly important to know the temperature parameters in which a particular IC operates.
The temperature level in a microprocessor (12) is typically measured by producing a voltage proportional to temperature, i.e., a temperature-dependent voltage. It is also useful to produce a temperature-independent voltage, i.e., insensitive to temperature, that can be processed along with the temperature-dependent voltage to allow for cancellation of process and supply variations. One method of generating a temperature-independent voltage and temperature-dependent voltage is by using a circuit known in the art as a temperature-independent and temperature-dependent voltage generator (xe2x80x9cTIDVGxe2x80x9d). A TIDVG typically requires a high voltage power supply, e.g., from 2 to 5 volts, in order to function correctly.
TIDVGs typically use both bipolar and MOS transistors. However, as MOS circuit elements used to construct a TIDVG continue to get smaller, scaling constraints imposed by the smaller MOS circuit elements require the use of a lower voltage power supply. Consequently, although a lower voltage power supply is required to power the TIDVG, the amount of voltage required to power devices like bipolar transistors does not decrease. As a result, there is less voltage to power the MOS transistors. Thus, the amount of voltage provided by the lower voltage power supply is not enough to power a TIDVG circuit configuration designed to be powered by a high voltage supply input. Therefore there is a need for a temperature-independent and temperature-dependent voltage generator that can be powered by a low voltage power supply.
According to one aspect of the present invention, an apparatus for generating a temperature-dependent voltage and a temperature-independent voltage comprises an amplifier stage that generates a feedback signal; a startup stage that generates a startup signal dependent on the feedback signal; and an output stage that outputs the temperature-dependent voltage and the temperature-independent voltage dependent on the feedback and startup signals.
According to another aspect, an apparatus for generating a temperature-dependent and a temperature-independent voltage comprises means for generating a feedback signal; means for generating a startup signal in relation to the feedback signal; means for generating a temperature-independent voltage in relation to the feedback signal and the startup signal; and means for generating a temperature-dependent voltage in relation to the temperature-independent voltage.
According to another aspect, a method for generating a temperature-dependent voltage and a temperature-independent voltage using a voltage generator having a power supply comprises generating a temperature-independent voltage using at least one temperature-sensitive element; and generating a temperature-dependent voltage in relation to the temperature-independent voltage, wherein the temperature-dependent voltage is generated using a temperature-sensitive element.
According to another aspect, a method for forcing a temperature-dependent and temperature-independent voltage generator out of a no-current state comprises generating a first temperature-sensitive voltage; generating a second temperature-sensitive voltage; generating a feedback signal by comparing the first temperature-sensitive voltage to the second temperature-sensitive voltage; generating a startup signal using the feedback signal; and inputting the startup signal to an output stage.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.